Thirteen-lined Ground Squirrels are often seen standing on their hind legs on roadsides or other places where grass is mowed, such as lawns, golf courses, or cemeteries. The squirrels probably once lived in short-grass prairie, and some human habitats suit them well. They dig a variety of burrows, from short ones used for escape to deeper, longer ones with nesting chambers. Like most ground squirrels, they hibernate. In hibernation, their heartbeat slows from more than 200 beats per minute to no more than five. How long they spend in hibernation annually depends on where they live, and at what elevation. Day length seems to determine when they enter hibernation in the fall, and some sort of internal clock prompts them to emerge in the spring. The Thirteen-lined Ground Squirrel's coat pattern is unique, with 13 dark and pale stripes running the length of the back; the dark stripes are patterned with small white spots.